The raw performance head to head, comparing Windows 8 to Windows 7, that I posted from PC World, are indisputable, irrespective of what any individual reviewer thinks of Windows 8. Windows 8 IS considerably faster on the same hardware, than Windows 7.
As far as the metro interface for the windows 8 tablet is concerned, its based on the same metro interface that Windows phone 7 has, and that has received plenty of rave reviews. I think some Windows 8 reviewers are not thinking sufficiently out of the box when it comes to metro.
Didn't you mean to say the current Windows 8 beta is faster? I hadn't heard that Win8 is released...
We'll see how things shake out when the final release ships.